It's good, but there are a few issues...
Plastering is a trade which often is subcontracted, hence a lot of the companies who operate in the area get work from other companies who they have done work for before. The low end of the market is all you'll get if you are a plasterer relying on doing work direct for end clients if you don't already have a good name - if you have a good name then you won't be wanting to buy a generic name.
It's definitely one for developing as a directory, but what's written above is something which means that anyone in the know about local services (especially the building trade, which is notoriously anti IT) is going to devalue the domain, not due to quality but due to what can be earned and how much work it takes to get direct advertisers onboard. AdSense for local plastering terms targets very poorly due to general building adverts being "close" - not a good thing when dealing with a specific service.
I expect that mid £xxx is where the value lies if selling to a domainer, more to an end user but low £xxxx is likely then - if you can find an interested plastering company.